/
explicit-function-return-type.ts
141 lines (132 loc) · 3.51 KB
/
explicit-function-return-type.ts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
import { TSESTree, AST_NODE_TYPES } from '@typescript-eslint/typescript-estree';
import * as util from '../util';
type Options = [
{
allowExpressions?: boolean;
allowTypedFunctionExpressions?: boolean;
}
];
type MessageIds = 'missingReturnType';
export default util.createRule<Options, MessageIds>({
name: 'explicit-function-return-type',
meta: {
type: 'problem',
docs: {
description:
'Require explicit return types on functions and class methods',
category: 'Stylistic Issues',
recommended: 'warn',
},
messages: {
missingReturnType: 'Missing return type on function.',
},
schema: [
{
type: 'object',
properties: {
allowExpressions: {
type: 'boolean',
},
allowTypedFunctionExpressions: {
type: 'boolean',
},
},
additionalProperties: false,
},
],
},
defaultOptions: [
{
allowExpressions: true,
allowTypedFunctionExpressions: false,
},
],
create(context, [options]) {
/**
* Checks if a node is a constructor.
* @param node The node to check
*/
function isConstructor(node: TSESTree.Node): boolean {
return (
node.type === AST_NODE_TYPES.MethodDefinition &&
node.kind === 'constructor'
);
}
/**
* Checks if a node is a setter.
* @param parent The node to check
*/
function isSetter(node: TSESTree.Node): boolean {
return (
node.type === AST_NODE_TYPES.MethodDefinition && node.kind === 'set'
);
}
/**
* Checks if a node is a variable declarator with a type annotation.
* @param node The node to check
*/
function isVariableDeclaratorWithTypeAnnotation(
node: TSESTree.Node,
): boolean {
return (
node.type === AST_NODE_TYPES.VariableDeclarator &&
!!node.id.typeAnnotation
);
}
/**
* Checks if a function declaration/expression has a return type.
* @param node The node representing a function.
*/
function checkFunctionReturnType(
node:
| TSESTree.ArrowFunctionExpression
| TSESTree.FunctionDeclaration
| TSESTree.FunctionExpression,
): void {
if (
!node.returnType &&
node.parent &&
!isConstructor(node.parent) &&
!isSetter(node.parent) &&
util.isTypeScriptFile(context.getFilename())
) {
context.report({
node,
messageId: 'missingReturnType',
});
}
}
/**
* Checks if a function declaration/expression has a return type.
* @param {ASTNode} node The node representing a function.
*/
function checkFunctionExpressionReturnType(
node:
| TSESTree.ArrowFunctionExpression
| TSESTree.FunctionDeclaration
| TSESTree.FunctionExpression,
): void {
if (
options.allowExpressions &&
node.parent &&
node.parent.type !== AST_NODE_TYPES.VariableDeclarator &&
node.parent.type !== AST_NODE_TYPES.MethodDefinition
) {
return;
}
if (
options.allowTypedFunctionExpressions &&
node.parent &&
isVariableDeclaratorWithTypeAnnotation(node.parent)
) {
return;
}
checkFunctionReturnType(node);
}
return {
ArrowFunctionExpression: checkFunctionExpressionReturnType,
FunctionDeclaration: checkFunctionReturnType,
FunctionExpression: checkFunctionExpressionReturnType,
};
},
});